WO2021145666A1

WO2021145666A1 - Power converting device, and vehicle including the same

Info

Publication number: WO2021145666A1
Application number: PCT/KR2021/000461
Authority: WO
Inventors: Chulwoo Park; Kanghwi KIM; Hosang JIN; Youngho CHAE; Woosup Kim
Original assignee: Lg Electronics Inc.
Priority date: 2020-01-14
Filing date: 2021-01-13
Publication date: 2021-07-22
Also published as: KR20210091603A

Abstract

The present disclosure relates to a power converting device, and a vehicle including the same. The power converting device according to an embodiment of the present disclosure includes: a first transformer; a second transformer connected in series to a primary side of the first transformer and connected in parallel to a secondary side of the first transformer; a first relay device connected to a node between the primary side of the first transformer and the primary side of the second transformer; a second relay device connected to the secondary side of the first transformer; wherein during power conversion output from the primary side to the secondary side, the first relay device is turned off and the second relay device is turned on, and during power conversion output from the secondary side to the primary side, the first relay device is turned on and the second relay device is turned off. Accordingly, bidirectional power conversion may be performed, and magnetizing inductance may be increased by using two transformers.

Description

POWER CONVERTING DEVICE, AND VEHICLE INCLUDING THE SAME

The present disclosure relates to a power converting device, and a vehicle including the same, and more particularly, to a power converting device capable of performing bidirectional power conversion and increasing magnetizing inductance by using two transformers, and a vehicle including the same.

Electric vehicles powered by electricity, hybrid vehicles that combine internal combustion engines with electric vehicles, or the like generate output using motors, batteries, and the like.

Meanwhile, a bidirectional converter is used for charging and discharging the battery in the vehicle.

A Chinese Patent No. CN208337415 (hereinafter referred to as "prior art 1") discloses a bidirectional converter. In prior art 1, however, the winding of a transformer is divided in half and a relay device is connected to one terminal, such that magnetizing inductance decreases due to the use of a single transformer, and a small magnetizing inductance may cause a rapid increase in slope of a current, thereby acting as a stress factor to switching elements.

Meanwhile, a US Patent No. US20080084714 (hereinafter referred to as "prior art 2") discloses a bidirectional converter. In prior art 2, however, there is a drawback in that although two transformers are used, the transformers are connected in parallel to each other, such that bidirectional conversion may not be performed.

It is an object of the present disclosure to provide a power converting device capable of performing bidirectional power conversion and increasing magnetizing inductance by using two transformers, and a vehicle including the same.

It is another object of the present disclosure to provide a power converting device capable of performing bidirectional power conversion and increasing magnetizing inductance during reverse power conversion by using two transformers, and a vehicle including the same.

It is yet another object of the present disclosure to provide a power converting device capable of forming the same topology or the same equivalent circuit during bidirectional power conversion, and a vehicle including the same.

In accordance with an aspect of the present disclosure, the above and other objects can be accomplished by providing a power converting device, and a vehicle including the same, the power converting device including: a first transformer; a second transformer connected in series to a primary side of the first transformer and connected in parallel to a secondary side of the first transformer; a first capacitor and a first inductor connected in series to a primary side of the second transformer; a first relay device connected to a node between the primary side of the first transformer and the primary side of the second transformer which are connected in series; a second relay device connected to the secondary side of the first transformer; and a second capacitor and a second inductor connected in series to a secondary side of the second transformer or the secondary side of the first transformer, wherein during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first relay device may be turned off and the second relay device may be turned on, and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device may be turned on and the second relay device may be turned off.

During the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first transformer and the second transformer may operate, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device may be turned on and only the second transformer may operate.

In addition, the power converting device may further include a controller configured to control the first relay device and the second relay device.

In this case, during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller may control the first relay device to be turned off and the second relay device to be turned on, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the first relay device to be turned on and the second relay device to be turned off.

Moreover, the power converting device may further include a controller configured to control the first relay device and the second relay device.

In this case, during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller may control the first transformer and the second transformer to operate, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the first relay device to be turned on and only the second transformer to operate.

Furthermore, the power converting device may further include: a first full bridge switching device electrically connected to the primary side of the first transformer and the primary side of the second transformer, and configured to perform a full bridge switching operation; and a second full bridge switching device electrically connected to the secondary side of the first transformer and the secondary side of the second transformer, and configured to perform a full bridge switching operation.

The first capacitor and the first inductor may be disposed between an output terminal of the first full bridge switching device and the primary side of the second transformer, and the second capacitor and the second inductor may be disposed between an input terminal of the second full bridge switching device and the secondary side of the second transformer.

The first full bridge switching device may include: first and second switching elements connected in parallel to each other; and third and fourth switching elements connected in series to the first and second switching elements, respectively, wherein the first relay device may be connected between a first node and the primary side of the first transformer, wherein the first node is disposed between the first switching element and the third switching element; and the first capacitor and the first inductor may be connected between a second node and the primary side of the second transformer, wherein the second node is disposed between the second switching element and the fourth switching element.

The second full bridge switching device may include: fifth and sixth switching elements connected in series to each other; and seventh and eighth switching elements connected in parallel to the fifth and sixth switching elements, and connected in series to each other, wherein the second capacitor and the second inductor may be connected between a third node and the secondary side of the second transformer, wherein the third node is disposed between the fifth switching element and the sixth switching element, and the second relay device may be connected between a fourth node and the secondary side of the second transformer, wherein the fourth node is disposed between the seventh switching element and the eighth switching element.

During the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control a transformer gain, based on at least one of the first transformer and the second transformer, to be less than 1.

Further, during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller may control the transformer gain, obtained by an operation of the first transformer and the second transformer, to be less than 1, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the transformer gain, obtained by an operation of the second transformer, to be less than 1.

In addition, during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the transformer gain to be stepped down.

Moreover, the power converting device may further include: a dc terminal capacitor disposed on an output terminal of the second full bridge switching device; an inverter connected to both ends of the dc terminal capacitor, and configured to convert direct current (DC) power to alternating current (AC) power; a switching device connected in parallel to the inverter; and a battery connected to the switching device.

Furthermore, the power converting device may further include a controller configured to control the first relay device, the second relay device, the first full bridge switching device, the second full bridge switching device, the inverter, and the switching device.

In accordance with another aspect of the present disclosure, the above and other objects can be accomplished by providing a power converting device, and a vehicle including the same, the power converting device including: a first transformer; a second transformer connected in series to a primary side of the first transformer and connected in parallel to a secondary side of the first transformer; a first capacitor and a first inductor connected in series to a primary side of the second transformer; a first relay device connected to a node between the primary side of the first transformer and the primary side of the second transformer which are connected in series; a second relay device connected to the secondary side of the first transformer; and a second capacitor and a second inductor connected in series to a secondary side of the second transformer or the secondary side of the first transformer, wherein during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first transformer and the second transformer may operate, and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device may be turned on and only the transformer may operate.

During the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller may control the first transformer and the second transformer to operate, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the first relay device to be turned on and only the second transformer to operate.

In addition, the power converting device may further include: a first full bridge switching device electrically connected to the primary side of the first transformer and the primary side of the second transformer, and configured to perform a full bridge switching operation; and a second full bridge switching device electrically connected to the secondary side of the first transformer and the secondary side of the second transformer, and configured to perform a full bridge switching operation.

During the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control a transformer gain, based on at least one of the first transformer and the second transformer, to be stepped down.

In a power converting device and a vehicle including the same according to an embodiment of the present disclosure, the power converting device includes: a first transformer; a second transformer connected in series to a primary side of the first transformer and connected in parallel to a secondary side of the first transformer; a first capacitor and a first inductor connected in series to a primary side of the second transformer; a first relay device connected to a node between the primary side of the first transformer and the primary side of the second transformer which are connected in series; a second relay device connected to the secondary side of the first transformer; and a second capacitor and a second inductor connected in series to a secondary side of the second transformer or the secondary side of the first transformer, wherein during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first relay device is turned off and the second relay device is turned on, and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device is turned on and the second relay device is turned off. Accordingly, bidirectional power conversion may be performed, and magnetizing inductance may be increased by using two transformers. Particularly, magnetizing inductance may be increased during reverse power conversion. Further, during bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

During the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first transformer and the second transformer may operate, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device may be turned on and only the second transformer may operate. Accordingly, bidirectional power conversion may be performed, and magnetizing inductance may be increased by using two transformers.

During the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller may control the first relay device to be turned off and the second relay device to be turned on, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the first relay device to be turned on and the second relay device to be turned off. Accordingly, bidirectional power conversion may be performed, and magnetizing inductance may be increased by using two transformers.

Further, during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller may control the first transformer and the second transformer to operate, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the first relay device to be turned on and only the second transformer to operate. Accordingly, bidirectional power conversion may be performed, and magnetizing inductance may be increased by using two transformers.

In addition, the power converting device may further include: a first full bridge switching device electrically connected to the primary side of the first transformer and the primary side of the second transformer, and configured perform a full bridge switching operation; and a second full bridge switching device electrically connected to the secondary side of the first transformer and the secondary side of the second transformer, and configured to perform a full bridge switching operation, thereby allowing bidirectional power conversion.

The first capacitor and the first inductor may be disposed between an output terminal of the first full bridge switching device and the primary side of the second transformer, and the second capacitor and the second inductor are electrically connected between an input terminal of the second full bridge switching device and the secondary side of the second transformer. Accordingly, during bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

The first full bridge switching device may include: first and second switching elements connected in parallel to each other; and third and fourth switching elements connected in series to the first and second switching elements, respectively, wherein the first relay device may be connected between a first node and the primary side of the first transformer, wherein the first node is disposed between the first switching element and the third switching element, and the first capacitor and the first inductor may be connected between a second node and the primary side of the second transformer, wherein the second node is disposed between the second switching element and the fourth switching element. Accordingly, during bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

The second full bridge switching device may include: fifth and sixth switching elements connected in series to each other; and seventh and eighth switching elements connected in parallel to the fifth and sixth switching elements, and connected in series to each other, wherein the second capacitor and the second inductor may be connected between a third node and the secondary side of the second transformer, wherein the third node is disposed between the fifth switching element and the sixth switching element, and the second relay device may be connected between a fourth node and the secondary side of the second transformer, wherein the fourth node is disposed between the seventh switching element and the eighth switching element. Accordingly, during bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

During the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control a transformer gain, based on at least one of the first transformer and the second transformer, to be less than 1. Accordingly, magnetizing inductance may be increased during bidirectional power conversion.

Further, during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller may control the transformer gain, obtained by an operation of the first transformer and the second transformer, to be less than 1, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the transformer gain, obtained by an operation of the second transformer, to be less than 1. Accordingly, magnetizing inductance may be increased during bidirectional power conversion.

In addition, during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the transformer gain to be stepped down. Accordingly, magnetizing inductance may be increased during bidirectional power conversion.

Moreover, the power converting device may further include: a dc terminal capacitor disposed on an output terminal of the second full bridge switching device; an inverter connected to both ends of the dc terminal capacitor, and configured to convert direct current (DC) power to alternating current (AC) power; a switching device connected in parallel to the inverter; and a battery connected to the switching device, thereby allowing charging and discharging of the battery.

In accordance with another aspect of the present disclosure, the above and other objects can be accomplished by providing a power converting device, and a vehicle including the same, the power converting device including: a first transformer; a second transformer connected in series to a primary side of the first transformer and connected in parallel to a secondary side of the first transformer; a first capacitor and a first inductor connected in series to a primary side of the second transformer; a first relay device connected to a node between the primary side of the first transformer and the primary side of the second transformer which are connected in series; a second relay device connected to the secondary side of the first transformer; and a second capacitor and a second inductor connected in series to a secondary side of the second transformer or the secondary side of the first transformer, wherein during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first transformer and the second transformer operate, and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device is turned on and only the second transformer operates. Accordingly, bidirectional power conversion may be performed, and magnetizing inductance may be increased by using two transformers. Particularly, magnetizing inductance may be increased during reverse power conversion. Further, during bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

During the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller may control the first transformer and the second transformer to operate, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control the first relay device to be turned on and only the second transformer to operate. Accordingly, bidirectional power conversion may be performed, and magnetizing inductance may be increased by using two transformers.

In addition, the power converting device may further include: a first full bridge switching device electrically connected to the primary side of the first transformer and the primary side of the second transformer, and configured to perform a full bridge switching operation; and a second full bridge switching device electrically connected to the secondary side of the first transformer and the secondary side of the second transformer, and configured to perform a full bridge switching operation, thereby allowing bidirectional power conversion.

Further, during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller may control a transformer gain, based on at least one of the first transformer and the second transformer, to be stepped down. Accordingly, magnetizing inductance may be increased during bidirectional power conversion.

The above and other objects, features and advantages of the present disclosure will be more apparent from the following detailed description in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view showing a vehicle body of a vehicle according to an embodiment of the present disclosure;

FIG. 2 is an example of an internal block diagram of the vehicle of FIG. 1;

FIG. 3 is an example of an internal block diagram of a motor drive device of FIG. 2;

FIG. 4 is an example of an internal circuit diagram of the motor drive device of FIG. 3;

FIG. 5 is an example of an internal block diagram of a controller of FIG. 4;

FIG. 6A is an example of a circuit diagram of a power converting device related to the present disclosure;

FIG. 6B is another example of a circuit diagram of a power converting device related to the present disclosure;

FIGS. 7A to 7F are diagrams for explaining operations of FIG. 6A or 6B;

FIG. 8 is an example of a circuit diagram of a power converting device according to an embodiment of the present disclosure; and

FIGS. 9A to 10B are diagrams for explaining FIG. 8.

Reference will now be made in detail to the preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. The suffixes "module" and "unit" in elements used in description below are given only in consideration of ease in preparation of the specification and do not have specific meanings or functions. Therefore, the suffixes "module" and "unit" may be used interchangeably.

FIG. 1 is a schematic view showing a vehicle body of a vehicle according to an embodiment of the present disclosure.

Referring to the drawing, a vehicle 100 according to an embodiment of the present disclosure may include a battery 205 for supplying power, a motor drive device 200 that is supplied with power from the battery 205, a motor 250 that is driven and rotated by the motor drive device 200, a front wheel 150 and a rear wheel 155 that are rotated by the motor 250, a front wheel suspension device 160 and a rear wheel suspension device 165 that prevent the vibration due to the road surface from being transmitted to a vehicle body, an inclination angle detector 190 for detecting the inclination angle of the vehicle body. Meanwhile, a drive gear (not shown) for converting the rotational speed of the motor 250 based on a gear ratio may be additionally provided.

The inclination angle detector 190 detects the inclination angle of the vehicle body, and the detected inclination angle is input to an electronic controller 410 described later. The inclination angle detector 190 may be implemented as a gyro sensor or a horizontal gauge sensor.

Meanwhile, the inclination angle detector 190 is illustrated as being disposed in the battery 205, but is not limited thereto. The inclination angle detector 190 may be disposed in the front wheel 150, the rear wheel 155, or in both the front wheel 150 and the rear wheel 155.

The battery 205 supplies power to the motor drive device 200. In particular, the DC power is supplied to a capacitor C in the motor drive device 200.

The battery 205 may be formed of a plurality of unit cells. The plurality of unit cells may be managed by a battery management system (BMS) to maintain a constant voltage, and may emit a constant voltage by the battery management system.

For example, the battery management system may detect the voltage Vbat of the battery 205, and transmit the detected voltage Vbat to an electronic controller (not shown) or an inverter controller 430 inside the motor drive device 200, may supply the DC power stored in a capacitor C in the motor drive device 200 to the battery when the battery voltage Vbat falls down to or below a lower limit. In addition, when the battery voltage Vbat rises up to or above an upper limit, DC power may be supplied to the capacitor C in the motor drive device 200.

The battery 205 is preferably configured as a secondary battery capable of charging and discharging, but is not limited thereto.

The motor drive device 200 receives DC power from the battery 205 via a power input cable 120. The motor drive device 200 converts the DC power received from the battery 205 into AC power and supplies to the motor 250. The converted AC power is preferably a three-phase AC power. The motor drive device 200 supplies three-phase AC power to the motor 250 through a three-phase output cable 125 provided in the motor drive device 200.

Although FIG. 1 shows that the motor drive device 200 has the three-phase output cable 125 composed of three cables, but three cables may be provided in a single cable.

Meanwhile, the motor drive device 200 according to an embodiment of the present disclosure will be described later with reference to FIG. 3 and below.

The motor 250 includes a stator 130 that is fixed without rotation and a rotor 135 that rotates. The motor 250 is provided with an input cable 140 to receive AC power supplied from the motor drive device 200. The motor 250 may be, for example, a three-phase motor, and the rotation speed of the rotor may be varied based on the applied frequency, when a voltage variable/frequency variable each phase AC power is applied to the coil of the stator of each phase.

The motor 250 may be implemented in various forms such as an induction motor, a blushless DC motor (BLDC) motor, a reluctance motor, and the like.

Meanwhile, one side of the motor 250 may be provided with a drive gear (not shown). The drive gear converts the rotational energy of the motor 250 based on the gear ratio. The rotational energy output from the drive gear is transmitted to the front wheel 150 and/or the rear wheel 155 to move the vehicle 100.

The front wheel suspension device 160 and the rear wheel suspension device 165 support the front wheel 150 and the rear wheel 155 respectively with respect to the vehicle body. The vertical direction of the front wheel suspension device 160 and the rear wheel suspension device 165 is supported by a spring or a damping mechanism so that the vibration due to the road surface does not affect the vehicle body.

The front wheel 150 may be further provided with a steering device (not shown). The steering device is a device for adjusting the direction of the front wheel 150 in order to drive the vehicle 100 in a direction intended by the driver.

Meanwhile, although not shown in the drawing, the vehicle 100 may further include an electronic controller for controlling the overall electronic devices in the vehicle. The electronic controller (not shown) controls each device to perform an operation, display, and the like. In addition, the above-described battery management system may be controlled.

Meanwhile, the electronic controller (not shown) may generate a driving command value according to various driving modes (traveling mode, reverse mode, neutral mode, parking mode, and the like) based on a detection signal from an inclination angle detector (not shown) for detecting the inclination angle of the vehicle 100, a speed detector (not shown) for detecting the speed of the vehicle 100, a brake detector (not shown) according to the motion of the brake pedal, an accelerator detector (not shown) according to the motion of the accelerator pedal, and the like. The driving command value at this time may be, for example, a torque command value.

Meanwhile, the vehicle 100 according to the embodiment of the present disclosure may include a hybrid electric vehicle using a battery and a motor while using an engine, as well as a pure electric vehicle using a battery and a motor.

In this case, the hybrid electric vehicle may further include a switching means capable of selecting at least one of a battery and an engine, and a transmission.

Meanwhile, the hybrid electric vehicle may be divided into a series method of driving the motor by converting the mechanical energy output from the engine into electrical energy, a parallel method of using the mechanical energy output from the engine and the electrical energy from the battery at the same time, and a series-parallel method of mixing them.

FIG. 2 is an example of an internal block diagram of the vehicle of FIG. 1.

Referring to FIG. 2, the vehicle 100 according to an embodiment of the present disclosure may include an input device 120, a memory 140, a controller 170, the motor drive device 200, and the battery 205.

The input device 120 may include an operation button, a key, and the like, and may output an input signal for power on/off, operation setting, etc., of the vehicle 100.

The memory 140 of the vehicle 100 may store data necessary for the operation of the vehicle 100. For example, the memory 140 may store data related to an operation time, an operation mode, and the like during operation of a motor drive device 200.

In addition, the memory 140 of the vehicle 100 may store management data including power consumption information of the vehicle, recommend driving information, current driving information, and management information.

In addition, the memory 140 of the vehicle 100 may store diagnostic data including operation information, driving information, and error information of the vehicle.

The controller 170 may control each unit in the vehicle 100. For example, the controller 170 may control the input device 120, the memory 140, the motor drive device 200, and the like.

The motor drive device 200 may be referred to as a motor drive device, as a motor drive device, to drive the motor 250.

The motor drive device 200 according to the embodiment of the present disclosure may include an inverter 420 having a plurality of switching elements and configured to convert DC power supplied from the battery 205 to output AC power to the motor 250, an output current detector E for detecting an output current io flowing through the motor 250, and the controller 170 for outputting a switching control signal to the inverter 420, based on current information (id, iq) based on the output current io detected by output current detector E and torque command value T*.

Meanwhile, the current information (id, iq) based on the output current io and the torque command value T* may be transmitted to the external server(not shown) or to the controller 170, and may receive a current command value (i*d, i*q) from the server (not shown) or the controller 170.

Accordingly, the motor 250 may be driven based on the current command value corresponding to the maximum torque calculated in real time by the server (not shown) or the controller 170. Thus, maximum torque drive of the motor 250 can be achieved.

A detailed operation of the motor drive device 200 will be described below with reference to FIG. 3.

FIG. 3 is an example of an internal block diagram of a motor drive device of FIG. 2.

Referring to FIG. 3, the motor drive device 200 according to the embodiment of the present disclosure is a drive device for driving the motor 250, and may convert input power to output predetermined output power. Accordingly, the motor drive device 200 may be referred to as a power converting device.

The motor drive device 200 may include: a dc/dc converter 410 for converting the level of DC power; the inverter 420 for outputting AC power by using the DC power from the dc/dc converter 410; the motor 250 being rotated by the AC power from the inverter 420; and a controller 430 for controlling the converter 410 and the inverter 420.

Further, the motor drive device 200 may include: a dc terminal capacitor C disposed on a dc terminal (a-b terminal) between the dc/dc converter 410 and the inverter 420; a switching device SWW connected in parallel to the inverter 420 and performing switching; and the battery 205 connected to the switching device SWW.

The dc/dc converter 410 may convert the DC power from a capacitor Ci, disposed on an input terminal (c-d terminal), and may output the converted DC power to the dc terminal (a-b terminal).

For example, if DC power from a charging device (not shown) is supplied to the input terminal (c-d terminal), the dc/dc converter 410 may convert the DC power from the charging device (not shown) and may output the converted DC power to the dc terminal (a-b terminal).

In another example, the dc/dc converter 410 may convert the level of the DC power at the dc terminal (a-b terminal), and may output the converted DC power to the input terminal (c-d terminal), thereby supplying the DC power to an external device (not shown) which is electrically connected to the input terminal (c-d terminal).

That is, the dc/dc converter 410 may be a bidirectional converter 410.

To this end, the dc/dc converter 410 may include a plurality of switching elements and a transformer. Further, the dc/dc converter 410 may convert DC power based on a switching operation of some of the plurality of switching elements, and may output the converted DC power to the input terminal (c-d terminal) or the dc terminal (a-b terminal).

In addition, the motor drive device 200 according to the embodiment of the present disclosure may further include: a dc terminal voltage detector B for detecting a dc terminal voltage Vdc; an output current detector E for detecting an output current flowing through the motor 250; and a position detection sensor 105 for detecting a position of a rotor of the motor 250.

The motor 250 according to the embodiment of the present disclosure may be a three-phase motor driven by the inverter 420.

The controller 430 may output a switching control signal Sic to the inverter 420, based on the current command value (i*d, i*q) corresponding to the calculated torque command value. Accordingly, maximum torque driving of the motor 250 can be achieved.

The controller 430 according to the embodiment of the present disclosure may control switching of the switching elements when the dc/dc converter 410 converts the level of the DC power.

For example, if the DC power from the charging device (not shown) is supplied to the input terminal (c-d terminal), the controller 430 may control the dc/dc converter 410 to convert the DC power from the charging device (not shown) and output the converted DC power to the dc terminal (a-b terminal).

In another example, the controller 430 may control the dc/dc converter 410 to convert the level of the DC power at the dc terminal (a-b terminal) and to output the converted DC power to the input terminal (c-d terminal).

In addition, the controller 430 calculates the current information (id, iq) and the torque command value T* in real time, calculates the current command value (i*d, i*q) based on the torque command value T*, and drives the motor 250 by using the current command value (i*d, i*q). Accordingly, the accuracy for high efficiency driving is improved.

The controller 430 calculates the current command value (i*d, i*q) based on the current information (id, iq), the torque command value T*, and the detected dc terminal voltage Vdc, and drives the motor 250 by using the current command value (i*d, i*q). Accordingly, the accuracy for high efficiency driving is improved.

FIG. 4 is an example of an internal circuit diagram of the motor drive device of FIG. 3.

Referring to FIG. 4, the motor drive device 200 according to an embodiment of the present disclosure may include the inverter 420, the controller 430, the output current detector E, a dc terminal voltage detector Vdc, and the position detection sensor 105.

The dc terminal capacitor C stores the power input to the dc terminal (a-b terminal). In the drawing, a single device is exemplified as the dc terminal capacitor C, but a plurality of devices may be provided to ensure device stability.

Meanwhile, the input power supplied to the dc terminal capacitor C may be a power stored in the battery 205 or a power that is level-converted by a converter (not shown).

Meanwhile, since both ends of the dc terminal capacitor C store the DC power, these may be referred to as a dc terminal or a dc link terminal.

The dc terminal voltage detector B may detect the voltage Vdc of the dc terminal that is both ends of the dc terminal capacitor C. To this end, the dc terminal voltage detector B may include a resistor, an amplifier, and the like. The detected dc terminal voltage Vdc, as a discrete signal in the form of a pulse, may be input to the controller 430.

The inverter 420 may include a plurality of inverter switching elements (Sa ~ Sc, S'a ~ S'c), and the turning on/off operation of the switching element (Sa ~ Sc, S'a ~ S'c) may convert the DC power Vdc into three-phase AC power Va, Vb, Vc having a certain frequency and output to the three-phase synchronous motor 250.

In the inverter 420, the upper arm switching element Sa, Sb, Sc and the lower arm switching element S'a, S'b, S'c which are connected in series with each other form a pair, and a total of three pairs of upper and lower arm switching elements are connected in parallel with each other (Sa&S'a, Sb&S'b, Sc&S'c). Diodes are connected in anti-parallel to each of the switching elements Sa, S'a, Sb, S'b, Sc, S'c.

The switching elements in the inverter 420 perform on/off operation of the respective switching elements based on the inverter switching control signal Sic from the inverter controller 430. Thus, the three-phase AC power having a certain frequency is output to the three-phase synchronous motor 250.

The controller 430 may control a switching operation of the inverter 420, based on a sensorless method.

To this end, the controller 430 may receive an output current io detected by the output current detector E.

The controller 430 may output an inverter switching control signal Sic to each gate terminal of the inverter 420 in order to control the switching operation of the inverter 420. Accordingly, the inverter switching control signal Sic may be referred to as a gate driving signal.

Meanwhile, the inverter switching control signal Sic is a switching control signal of the pulse width modulation method PWM, and is generated and output based on the output current io detected by the output current detector E.

The output current detector E detects the output current io flowing between the inverter 420 and the three-phase motor 250. That is, the current flowing in the motor 250 may be detected.

The output current detector E may detect all of the output currents ia, ib, ic of each phase, or may detect the output currents of two phases by using three-phase equilibrium.

The output current detector E may be positioned between the inverter 420 and the motor 250, and a current transformer (CT), a shunt resistor, or the like may be used for current detection.

The detected output current io, as a discrete signal in the form of a pulse, may be applied to the controller 430, and a switching control signal Sic is generated based on the detected output current io.

Meanwhile, the three-phase motor 250 includes a stator and a rotor, and AC power of each phase having a certain frequency is applied to a coil of the stator of each phase (a, b, c phase), so that the rotor rotates.

Such a motor 250 may include, for example, a Surface-Mounted Permanent-Magnet Synchronous Motor (SMPMSM), an Interior Permanent Magnet Synchronous Motor (IPMSM), a Synchronous Reluctance Motor (Synrm), and the like. Among these, SMPMSM and IPMSM are a permanent magnet synchronous motor (PMSM) to which permanent magnet is applied, and Synrm has no permanent magnet.

Meanwhile, the motor 250 according to the embodiment of the present disclosure is described mainly based on an Interior Permanent Magnet Synchronous Motor (IPMSM).

FIG. 5 is an example of an internal block diagram of a controller of FIG. 4.

Referring to FIG. 5, the controller 430 of FIG. 5 may receive the detected output current io from the output current detector 320, and receive rotor position information θ of the motor 250 from the position detection sensor 105.

The position detection sensor 105 may detect the magnetic pole position е of the rotor of the motor 250. That is, the position detection sensor 105 may detect the position of the rotor of the motor 250.

To this end, the position detection sensor 105 may include an encoder, a resolver, or the like.

In the following descriptions, the coordinate system and coordinate axis used are defined here.

The αβ coordinate system is a two-dimensional fixed coordinate system whose axes are α and β axes which are fixed axes. The α and β axes are orthogonal to each other, and the β axis leads the α axis by electrical angle 90˚.

The dq coordinate system is a two-dimensional rotary coordinate system having d and q axes that are rotational axis. In the rotary coordinate system that rotates at the same speed as the rotational speed of the magnetic flux made by the permanent magnet of the motor 250, the axis according to the direction of the magnetic flux made by the permanent magnet is the d axis, and the axis that leads the d axis by electrical angle 90˚ degrees is the q axis.

Referring to FIG. 5, the controller 430 may include a speed calculator 320, an axis conversion unit 310, a torque calculator 325, a magnetic flux estimator 327, a current command generation unit 330, a voltage command generation unit 340, an axis conversion unit 350, and a switching control signal output unit 360.

The axis conversion unit 310 in the controller 430 receives the three-phase output current (ia, ib, ic) detected by the output current detector E, and converts the three-phase output current into a two-phase current (iα, iβ) of the stationary coordinate system.

Meanwhile, the axis conversion unit 310 may convert the two-phase current (iα, iβ) of the stationary coordinate system into a two-phase current (id, iq) of the rotary coordinate system.

The speed calculator 320 in the controller 430 estimates the rotor position

of the motor 250, based on the two-phase current (iα, iβ) of the stationary coordinate system converted by the axis conversion unit 310. In addition, based on the estimated rotor position

, the calculated speed

may be output.

The torque calculator 325 in the controller 430 may calculate the current torque T, based on the calculated speed

.

The magnetic flux estimator 327 may estimate a magnetic flux (λ) of the motor 250.

Particularly, the magnetic flux estimator 327 may estimate the magnetic flux (λ) of the motor 250 based on the output current io, flowing through the motor 250, and a voltage command value.

More specifically, the magnetic flux estimator 327 may estimate the magnetic flux (λ) of the motor 250 based on the two-phase current (id, iq) of the rotary coordinate system, which is based on the output current flowing through the motor 250, and voltage command values (V*d, V*q) generated by the voltage command generation unit 340.

The current command generation unit 330 in the controller 430 generates the current command values (i*d, i*q), based on the calculated current torque T and the torque command value T*.

For example, the current command generation unit 330 performs a PI control in a PI controller 335, based on the calculated current torque T and the torque command value T*, and may generate the current command value (i*d, i*q). Meanwhile, the value of the d-axis current command value i*d may be set to zero.

Meanwhile, the current command generation unit 330 may further include a limiter (not shown) for restricting the level so that the current command value (i*d, i*q) does not exceed an allowable range.

Next, the voltage command generation unit 340 generates d-axis and q-axis voltage command values (V*d, V*q), based on the d-axis and q-axis currents (id, iq) that are axis-converted into two-phase rotary coordinate system by the axis conversion unit, and the current command value (i*d, i*q) in the current command generation unit 330, or the like.

For example, the voltage command generation unit 340 may perform the PI control in the PI controller 344, based on a difference between the q-axis current iq and the q-axis current command value i*q, and may generate the q-axis voltage command value V*q. In addition, the voltage command generation unit 340 may perform the PI control in the PI controller 348, based on a difference between the d-axis current id and the d-axis current command value i*d, and may generate the d-axis voltage command value V*d. Meanwhile, the value of the d-axis voltage command value V*d may be set to zero, in correspondence with the case where the value of the d-axis current command value i*d is set to zero.

Meanwhile, the voltage command generation unit 340 may further include a limiter (not shown) for restricting the level so that the d-axis and q-axis voltage command values (V*d, V*q) do not exceed the allowable range.

Meanwhile, the generated d-axis and q-axis voltage command values (V*d, V*q) are input to the axis conversion unit 350.

The axis conversion unit 350 receives the position

calculated by the speed calculator 320 and the d-axis and q-axis voltage command values (V*d, V*q), and performs axis conversion.

First, the axis conversion unit 350 performs conversion from a two-phase rotary coordinate system to a two-phase stationary coordinate system. In this case, the position

calculated by the speed calculator 320 may be used.

In addition, the axis conversion unit 350 performs conversion from two-phase stationary coordinate system to three-phase stationary coordinate system. Through this conversion, the axis conversion unit 350 outputs the three-phase output voltage command value (V*a, V*b, V*c).

The switching control signal output unit 360 generates and outputs a switching control signal Sic according to the pulse width modulation PWM method based on the three-phase output voltage command value (V*a, V*b, V*c).

The output inverter switching control signal Sic may be converted into a gate driving signal by a gate motor drive device (not shown), and input to the gate of each switching element in the inverter 420. Thus, each of the switching elements (Sa, S'a, Sb, S'b, Sc, S'c) in the inverter 420 performs a switching operation.

FIG. 6A is an example of a circuit diagram of a power converting device related to the present disclosure.

Referring to FIG. 6A, a general power converting device 600a, which is a bidirectional converter, includes: a transformer T; a full-bridge switching device SWUa provided on an input side of the transformer T and having a plurality of switching elements Q1 to Q4; a full-bridge diode unit DUb provided on an output side of the transformer T and having a plurality of diode elements D1 to D4; a first inductor Lp connected to one end of the transformer T; and a first capacitor Cp connected to the other end of the input side of the transformer T.

The power converting device 600a of FIG. 6A is a unidirectional resonant dc/dc converter, and may be an LLC dc/dc converter.

However, the power converting device 600a of FIG. 6A has a drawback in that the power converting device 600a may not perform bidirectional power conversion.

FIG. 6B is another example of a circuit diagram of a power converting device related to the present disclosure.

Referring to FIG. 6B, a general power converting device 600b, which is a bidirectional converter, includes: a transformer T; a first full-bridge switching device SWUa provided on an input side of the transformer T and having a plurality of switching elements Q1 to Q4; a second full-bridge switching device SWUb provided on an output side of the transformer T and having a plurality of diode elements Q5 to Q8; a first inductor Lr1 connected to one end nia of an input side of the transformer T; a first capacitor Cr1 connected to the other end nib of the input side of the transformer T; a second inductor Lr2 connected to one end noa of an output side of the transformer T; and a second capacitor Cr2 connected to the other end nob of the output side of the transformer T.

The power converting device 600b of FIG. 6B may be a bidirectional CLLC dc/dc converter.

That is, the dc/dc converter has a symmetrical structure in which, with respect to the transformer T, the first capacitor Cr1 and the first inductor Lr1 are electrically connected on the input side of the transformer T, and the second inductor Lr2 and the second capacitor Cr2 are electrically connected on the output side thereof.

However, in the power converting device 600b of FIG. 6B, during power conversion in a forward direction from the input side to the output side and during power conversion in a reverse direction from the output side to the input side, a resonant frequency value varies according to a difference in inductance between the first inductor Lr1 and the second inductor Lr2, and a difference in capacitance between the first capacitor Cr1 and the second capacitor Cr2.

That is, a resonant frequency in the forward direction may be different from a resonant frequency in the reverse direction, thereby causing a problem in that different driving methods are required for power conversion in the respective directions.

FIGS. 7A to 7F are diagrams for explaining operations of FIG. 6A or 6B.

First, FIG. 7A is a diagram illustrating an example of a resonant tank circuit in the power converting device 600b including the bidirectional CLLC dc/dc converter of FIG. 6B.

Referring to FIG. 7A, an input side n1-n2 of the transformer T forms a resonant circuit with Lr, Lm1, and Cr, and an output side n3-n4 of the transformer T forms a resonant circuit with Lr, Lm2, and Cr.

In FIG. 7A, Np may be a turns ratio at the input side n1-n2 of the transformer T, and Ns may be a turns ratio at the output side n3-n4 thereof.

If both input/output voltages of the dc/dc converter are representative of a variable condition, or if one of the voltages is not much greater than the other, all gains are required to be variable in both step-up and step-down ranges.

For example, in order to ensure advantages in terms of design and control, if Np or Ns is of a higher value, gains of the LC resonant tank circuit of FIG. 7A are required to be variable over the widest possible range from the step-up range to the step-down range.

FIG. 7B illustrates a resonant gain versus frequency curve of the bidirectional resonant converter of FIG. 6B.

Referring to FIG. 7B, a plurality of gain curves Cvba to CVbc are shown, in which CVba indicates a light load, CVbc indicates a heavy load, and CVbb indicates a medium load.

In the plurality of gain curves CVba to CVbc, a resonant gain is 1 at a resonance point.

In FIG. 7B, ref indicates a frequency at which resonance occurs, in which case a gain may be 1.

Further, a region having frequencies less than ref (or a region having a gain greater than 1) may be referred to as a Below resonance region Ara, and a region having frequencies greater than ref (or a region having a gain less than 1) may be referred to as an Above resonance region Arb.

As illustrated in FIG. 6B, if the transformer T which provides a single constant gain is used, gains over a wide input and output range may not be provided individually, such that an actual resonant tank circuit determines a gain for the entire range of operation.

As shown in the resonant tank gain curve, it can be seen that a rapid change in gain is observed with a high slope on the left side of the resonant frequency ref, while on the right side of the resonant frequency ref, the change slows down but the gain is not close to 0.

Accordingly, it is desired that a turns ratio of the transformer T, which is a single constant gain, be step-down when generally viewed from the output side of the transformer T, in order to further provide a damping ratio on the right side of the resonant frequency ref.

FIG. 7C illustrates an example of an equivalent circuit of a transformer when the bidirectional resonant converter of FIG. 6B operates in a forward direction.

That is, FIG. 7C illustrates an equivalent model of the transformer T during power conversion from an input side nia-nib to an output side noa-nob of the transformer T in the bidirectional resonant converter of FIG. 6B.

Referring to FIG. 7C, when viewed from the input side nia-nib of the transformer T, a magnetizing inductance Lm1 and a turns ratio n are constants of the equivalent model based on the following Equation 1.

[Equation 1]

n = Ns/Np

Herein, n is the turns ratio of the transformer T, Np is a turns ratio at the input side n1-n2, and Ns is a turn ratio at the output side n3-n4.

FIG. 7D is a diagram illustrating an example of an equivalent model of a transformer when the bidirectional resonant converter of FIG. 6B operates in a reverse direction.

That is, FIG. 7D illustrates an equivalent model of the transformer T during power conversion from the output side noa-nob to the input side nia-nib of the transformer T in the bidirectional resonant converter of FIG. 6B.

Referring to FIG. 7D, when viewed from the output side noa-nob of the transformer T, a magnetizing inductance Lm2 and a turns ratio N are constants of the equivalent model based on the following Equation 2.

[Equation 2]

N = Np/Ns

Herein, N is the turns ratio, Np is a turns ratio at the input side n1-n2, and Ns is a turns ratio at the output side n3-n4.

If Np, which is the turns ratio at the input side n1-n2, is greater than Ns which is the turns ratio at the output side n3-n4, i.e., if the turns ratios are step down, magnetizing inductances Lm1 and Lm2 may be represented by the following Equations 3 and 4.

[Equation 3]

Lm2 = Lm1 * (Ns²)/(Np²)

[Equation 4]

Lm1 >> Lm2

Based on Equation 4, the forward magnetizing inductance Lm1 is much greater than the reverse magnetizing inductance Lm2.

FIG. 7E is a diagram illustrating a waveform of a current, flowing through a resonant tank, in Below resonance region Ara of FIG. 7B.

Referring to FIG. 7E, power conversion is performed in a period Ta1 of resonance between the resonant inductor Lr1 and a resonant capacitor Cr1, such that power is transmitted to the output side of the transformer T; and during a period Ta2 when the resonance is terminated, the Lm current, which is a magnetizing current, circulates.

FIG. 7F is a diagram illustrating a waveform of a current, flowing through a resonant tank, in the resonance period ref of FIG. 7B.

Referring to FIG. 7F, in the resonance period ref and Above resonance region Arb, the Lm current, which is a magnetizing current, does not circulate unlike FIG. 7E.

As described above, in the resonant converter using a transformer having a single fixed turns ratio, there is a drawback in that as the forward magnetizing inductance Lm1 is much greater than the reverse magnetizing inductance Lm2, a significant loss occurs.

Accordingly, there is a need for a method to increase the reverse magnetizing inductance Lm2, as well as the forward magnetizing inductance Lm1.

In this embodiment of the present disclosure, there is provided a method of increasing the reverse magnetizing inductance Lm2 as well as the forward magnetizing inductance Lm1, which will be described below with reference to FIG. 8 and the following figures.

FIG. 8 is an example of a circuit diagram of a power converting device according to an embodiment of the present disclosure, and FIGS. 9A to 10B are diagrams for explaining FIG. 8.

Referring to FIG. 8, a power converting device 800 according to an embodiment of the present disclosure includes: a first transformer T1; a second transformer T2 connected in series to a primary side nia-nib of the first transformer T1 and connected in parallel to a secondary side noa-nob of the first transformer T1; a first capacitor Cr1 and a first inductor Lr1 connected in series to a primary side nib-nic of the second transformer T2; a first relay device RLY1 connected to a node between the primary side nia-nib of the first transformer T1 and the primary side nib-nic of the second transformer T1, which are connected in series to each other; a second relay device RLY2 connected to the secondary side noa-nob of the first transformer T1; and a second capacitor Cr2 and a second inductor Lr2 connected to a secondary side noc-nod of the second transformer T2.

Meanwhile, during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, i.e., during forward power conversion, and during power conversion output from the primary side nia-nib to the secondary side noa-nob (forward output) as illustrated in FIG. 9A, the first relay device RLY1 is turned off and the second relay device RLY2 is turned on.

In addition, during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, i.e., during reverse power conversion, the first relay device RLY1 is turned on and the second relay device RLY2 is turned off, as illustrated in FIG. 9B. Accordingly, bidirectional power conversion may be performed, and the magnetizing inductance may be increased using two transformers. Particularly, the magnetizing inductance during the reverse power conversion may be increased, and during the bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

In addition, the first full bridge switching device SWUa may include first and second switching elements Q1 and Q2 connected in parallel to each other, and third and fourth switching elements Q3 and Q4 connected in series to the first and second switching elements Q1 and Q2, respectively.

In this case, the primary side nia-nib of the transformer T may be connected between a first node n1, disposed between the first switching element Q1 and the third switching element Q3, and a second node n2 disposed between the second switching element Q2 and the fourth switching element Q4.

Specifically, the first relay device RLY1 is connected between the first node n1, disposed between the first switching element Q1 and the third switching element Q3, and the primary side nia-nib of the first transformer T1; and the first capacitor Cr1 and the first inductor Lr1 are connected between the second node n2, disposed between the second switching element Q2 and the fourth switching element Q4, and the primary side nib-nic of the second transformer T2. Accordingly, during the bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

Further, the second full bridge switching device SWUb may include fifth and sixth switching elements Q5 and Q6 connected in series to each other, and seventh and eighth switching elements Q7 and Q8 connected in parallel to the fifth and sixth switching elements Q5 and Q6 and connected in series to each other.

In this case, the secondary side noa-nob of the transformer T may be connected between a third node n3, disposed between the fifth switching element Q5 and the sixth switching element Q5, and a fourth node n4 disposed between the seventh switching element Q7 and the eighth switching element Q8.

Specifically, the second capacitor Cr2 and the second inductor Lr2 are connected between the third node n3, disposed between the fifth switching element Q5 and the sixth switching element Q6, and the secondary side noc-nod of the second transformer T2; and the second relay device RLY2 is connected between the fourth node n4, disposed between the seventh switching element Q7 and the eighth switching element Q8, and the secondary side noc-nod of the second transformer T2. Accordingly, during the bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

In addition, during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, i.e., during forward power conversion, the controller 430 may control the first transformer T1 and the second transformer T2 to operate; and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, i.e., during reverse power conversion, the controller 430 may control the first relay device RLY1 to be turned on and only the second transformer T2 to operate, thereby enabling bidirectional power conversion and increasing magnetizing inductance by using two transformers. Particularly, magnetizing inductance during the reverse power conversion may be increased, and during the bidirectional power conversion, the same topology or the same equivalent circuit may be formed.

Further, during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, i.e., during forward power conversion, and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller 430 may control a transformer gain, which is based on at least either the first transformer T1 or the second transformer T2, to be less than 1, thereby increasing magnetizing inductance during bidirectional power conversion.

During power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, i.e., during forward power conversion, the controller 430 may control the transformer gain, obtained by the operation of the first transformer T1 and the second transformer T2, to be less than 1; and during power conversion from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, i.e., during reverse power conversion, the controller 430 may control the transformer gain, obtained by the operation of the second transformer T2, to be less than 1, thereby increasing magnetizing inductance during the bidirectional power conversion.

Further, during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, i.e., during forward power conversion, and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller 430 may control the transformer gain to be stepped down, thereby increasing magnetizing inductance during the bidirectional power conversion.

FIGS. 9A and 10A are diagrams illustrating an example of a forward operation of the power converting device 800 of FIG. 8.

Referring to FIGS. 9A and 10A, the first relay RLY1 is turned off, and the second relay device RLY2 is turned on.

As the first relay device RLY1 is turned off, the first node n1 and nia, which is the input side of the first transformer T1, are electrically connected to each other. Further, the second node n2 and nic, which is the input side of the second transformer T2, are electrically connected to each other.

Particularly, the first inductor Lr1 and the first capacitor Cr1 are connected between the second node n2 and nic which is the input side of the second transformer T2.

As the second relay device RLY2 is turned on, the fourth node n4 and noa, which is the output side of the first transformer T1, are electrically connected to each other. Further, noa, which is the output side of the first transformer T1, and noc, which is the output side of the second transformer T2, are connected in parallel to each other.

In addition, the third node n3 and nob, which is the output side of the first transformer T1, are electrically connected to each other.

Particularly, the second inductor Lr2 and the second capacitor Cr2 are connected between the third node n3 and nob which is the output side of the first transformer T1.

Furthermore, nob, which is the output side of the first transformer T1, and nod, which is the output side of the second transformer T2, are connected in parallel to each other.

FIGS. 9B and 10B are diagrams illustrating an example of a reverse operation of the power converting device 800 of FIG. 8.

Referring to FIGS. 9B and 10B, the first relay RLY1 is turned on, and the second relay device RLY2 is turned off.

As the first relay device RLY1 is turned on, a short occurs between the first node n1 and nia, which is the input side of the first transformer T1, such that the first node n1 and nib, which is the input side of the first transformer T1, are electrically connected to each other. Further, the second node n2 and nic, which is the input side of the second transformer T2, are electrically connected to each other.

As the second relay device RLY2 is turned off, the fourth node n4 and noa, which is the output side of the first transformer T1, are open.

Accordingly, the fourth node n4 and noc, which is the output side of the second transformer T2, are electrically connected to each other.

As nob, which is the output side of the first transformer T1, and nod, which is the output side of the second transformer T2, are connected in parallel to each other, the third node n3 and nod, which is the output side of the second transformer T2, are electrically connected to each other.

Particularly, the second inductor Lr2 and the second capacitor Cr2 are connected between the third node n3 and nod which is the output side of the second transformer T2.

The operations in FIGS. 9A to 10B may be expressed by the following Equations 5 to 7.

[Equation 5]

[Equation 6]

Lm11 denotes the magnetizing inductance at the input side of the first transformer T1; Lm12 denotes the magnetizing inductance at the input side of the second transformer T2; Lm21 denotes the magnetizing inductance at the output side of the first transformer T1; and Lm22 denotes the magnetizing inductance at the output side of the second transformer T2.

A turns ratio between the input side of first transformer T1 and the input side of the second transformer T2, connected in series to each other, may be k*Np/2; and a turns ratio between the output side of the first transformer T1 and the output side of the second transformer T2, connected in parallel to each other, may be k*Ns.

Lm1 denotes an input-side magnetizing inductance of the first transformer T1 and the second transformer T2, and Lm2 denotes an output-side magnetizing inductance of the first transformer T1 and the second transformer T2.

As the input sides of the first transformer T1 and the second transformer T2 are connected in series to each other, Lm1 may be a sum of Lm11 and Lm12.

In this case, Lm11 and Lm12 may be equal to each other, and Lm21 and Lm22 may be equal to each other.

Further, the following Equation 7 may be represented by a combination of Equations 5 and 6.

[Equation 7]

That is, it can be seen that during the reverse operation in FIG. 9B or 10B, an equivalent capacity of Lm2 is increased by two times an existing equivalent capacity of FIG. 6B.

That is, during the reverse operation illustrated in FIG. 9B or 10B, it is possible to prevent reduction in magnetizing inductance and to increase magnetizing inductance in the reverse direction, thereby providing wider input and output gain ranges.

The following Equation 8 shows forward gain.

[Equation 8]

Herein, Np denotes a turns ratio at the input side of the first transformer T1. In this case, a turns ratio at the input side of the first transformer T1 may be equal to a turns ratio at the input side of the second transformer T2, and Np may be a turns ratio at the input side of the first transformer T1 or at the input side of the second transformer T2.

Further, Ns may be a turns ratio at the output side of the first transformer T1. In this case, a turns ratio at the output side of the first transformer T1 may be equal to a turns ratio at the output side of the second transformer T2, and Ns may be a turns ratio at the output side of the first transformer T1 or at the output side of the second transformer T2.

Based on Equation 8, the forward gain Gain_forward is less than 1.

The following Equation 9 shows reverse gain Gain_reverse.

[Equation 9]

In Equation 9, if a value of Np is less than two times a value of Ns, the reverse gain Gain_reverse is less than 1.

For example, if a value of Np is less than two times a value of Ns, and as the value of Np decreases, the reverse gain Gain_reverse becomes less than 1.

Accordingly, in order to control the reverse gain Gain_reverse to be less than 1, it is desirable that the value of Np is less than two times the value of Ns.

Accordingly, referring to FIGS. 8 to 10B, there is an effect in that a transformer transfer ratio may be provided as a step-down ratio in both the forward and reverse directions.

In addition, during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, i.e., during forward power conversion, and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller 430 may control the transformer gain, which is based on at least either the first transformer T1 or the second transformer T2, to be less than 1, thereby increasing magnetizing inductance during the bidirectional power conversion.

Furthermore, during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, i.e., during forward power conversion, the controller 430 may control the transformer gain, obtained by the operation of the first transformer T1 and the second transformer T2,to be less than 1; and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, i.e., during reverse power conversion, the controller 430 may control the transformer gain, obtained by the operation of the second transformer T2, to be less than 1, thereby increasing magnetizing inductance during the bidirectional power conversion.

In addition, during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, i.e., during forward power conversion, and during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller 430 may control the transformer gain to be stepped down, thereby increasing magnetizing inductance during the bidirectional power conversion.

Accordingly, it is desirable that during the forward power conversion, the controller 430 controls the power converting device to operate as illustrated in FIG. 9A, and during the reverse power conversion, the controller 430 controls the power converting device to operate as illustrated in FIG. 9B.

In this manner, bidirectional power conversion may be performed, and magnetizing inductance may be increased by using two transformers. In addition, during the bidirectional power conversion, the same equivalent circuit may be formed by using the same topology.

The power converting device according to the embodiment of the present disclosure, and the vehicle having the same are not limited to the configuration and method of the embodiments as described above, but all or part of each of the embodiments may be configured to be selectively combined to achieve various modifications.

Although the exemplary embodiments of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Accordingly, the scope of the present disclosure is not construed as being limited to the described embodiments but is defined by the appended claims as well as equivalents thereto.

The present disclosure is applicable to a power converting device, and a vehicle including the same.

Claims

A power converting device comprising:

a first transformer;

a second transformer connected in series to a primary side of the first transformer and connected in parallel to a secondary side of the first transformer;

a first capacitor and a first inductor connected in series to a primary side of the second transformer;

a first relay device connected to a node between the primary side of the first transformer and the primary side of the second transformer which are connected in series;

a second relay device connected to the secondary side of the first transformer; and

a second capacitor and a second inductor connected in series to a secondary side of the second transformer or the secondary side of the first transformer,

wherein during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first relay device is turned off and the second relay device is turned on, and

wherein during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device is turned on and the second relay device is turned off.
The power converting device of claim 1, wherein during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first transformer and the second transformer operate, and

wherein during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device is turned on and only the second transformer operates.
The power converting device of claim 1, further comprising a controller configured to control the first relay device and the second relay device,

wherein during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller controls the first relay device to be turned off and the second relay device to be turned on, and

wherein during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller controls the first relay device to be turned on and the second relay device to be turned off.
The power converting device of claim 1, further comprising a controller configured to control the first relay device and the second relay device,

wherein during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller controls the first transformer and the second transformer to operate, and

wherein during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller controls the first relay device to be turned on and only the second transformer to operate.
The power converting device of claim 1, further comprising:

a first full bridge switching device electrically connected to the primary side of the first transformer and the primary side of the second transformer, and configured perform a full bridge switching operation; and

a second full bridge switching device electrically connected to the secondary side of the first transformer and the secondary side of the second transformer, and configured to perform a full bridge switching operation.
The power converting device of claim 5, wherein the first capacitor and the first inductor are electrically connected between an output terminal of the first full bridge switching device and the primary side of the second transformer, and

wherein the second capacitor and the second inductor are electrically connected between an input terminal of the second full bridge switching device and the secondary side of the second transformer.
The power converting device of claim 5, wherein the first full bridge switching device comprises:

first and second switching elements connected in parallel to each other; and

third and fourth switching elements connected in series to the first and second switching elements, respectively,

wherein the first relay device is connected between a first node and the primary side of the first transformer, wherein the first node is disposed between the first switching element and the third switching element, and

wherein the first capacitor and the first inductor are connected between a second node and the primary side of the second transformer, wherein the second node is disposed between the second switching element and the fourth switching element.
The power converting device of claim 5, wherein the second full bridge switching device comprises:

fifth and sixth switching elements connected in series to each other; and

seventh and eighth switching elements connected in parallel to the fifth and sixth switching elements, and connected in series to each other,

wherein the second capacitor and the second inductor are connected between a third node and the secondary side of the second transformer, wherein the third node is disposed between the fifth switching element and the sixth switching element, and

wherein the second relay device is connected between a fourth node and the secondary side of the second transformer, wherein the fourth node is disposed between the seventh switching element and the eighth switching element.
The power converting device of claim 3, wherein during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controllr controls a transformer gain, based on at least one of the first transformer and the second transformer, to be less than 1.
The power converting device of claim 3, wherein during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller controls the transformer gain, obtained by an operation of the first transformer and the second transformer, to be less than 1, and

Wherein during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller controls the transformer gain, obtained by an operation of the second transformer, to be less than 1.
The power converting device of claim 3, wherein during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller controls the transformer gain to be stepped down.
The power converting device of claim 5, further comprising:

a dc terminal capacitor disposed on an output terminal of the second full bridge switching device;

an inverter connected to both ends of the dc terminal capacitor, and configured to convert direct current (DC) power to alternating current (AC) power;

a switching device connected in parallel to the inverter; and

a battery connected to the switching device.
The power converting device of claim 12, further comprising a controller configured to control the first relay device, the second relay device, the first full bridge switching device, the second full bridge switching device, the inverter, and the switching device.
A power converting device comprising:

a first transformer;

a second transformer connected in series to a primary side of the first transformer and connected in parallel to a secondary side of the first transformer;

a first capacitor and a first inductor connected in series to a primary side of the second transformer;

a first relay device connected to a node between the primary side of the first transformer and the primary side of the second transformer which are connected in series;

a second relay device connected to the secondary side of the first transformer; and

a second capacitor and a second inductor connected in series to a secondary side of the second transformer or the secondary side of the first transformer,

wherein during power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the first transformer and the second transformer operate, and

wherein during power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the first relay device is turned on and only the second transformer operates.
The power converting device of claim 14, further comprising a controller configured to control the first relay device and the second relay device,

wherein during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, the controller controls the first transformer and the second transformer to operate; and

wherein during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller controls the first relay device to be turned on and only the second transformer to operate.
The power converting device of claim 14, further comprising:

a first full bridge switching device electrically connected to the primary side of the first transformer and the primary side of the second transformer, and configured to perform a full bridge switching operation; and

a second full bridge switching device electrically connected to the secondary side of the first transformer and the secondary side of the second transformer, and configured to perform a full bridge switching operation.
The power converting device of claim 16, wherein the first full bridge switching device comprises:

first and second switching elements connected in parallel to each other; and

third and fourth switching elements connected in series to the first and second switching elements, respectively,

wherein the first relay device is connected between a first node and the primary side of the first transformer, wherein the first node is disposed between the first switching element and the third switching element, and

wherein the first capacitor and the first inductor are connected between a second node and the primary side of the second transformer, wherein the second node is disposed between the second switching element and the fourth switching element.
The power converting device of claim 16, wherein the second full bridge switching device comprises:

fifth and sixth switching elements connected in series to each other; and

seventh and eighth switching elements connected in parallel to the fifth and sixth switching elements, and connected in series to each other,

wherein the second capacitor and the second inductor are connected between a third node and the secondary side of the second transformer, wherein the third node is disposed between the fifth switching element and the sixth switching element, and

wherein the second relay device is connected between a fourth node and the secondary side of the second transformer, wherein the fourth node is disposed between the seventh switching element and the eighth switching element.
The power converting device of claim 15, wherein during the power conversion output from the primary side of the first transformer or the second transformer to the secondary side of the first transformer or the second transformer, and during the power conversion output from the secondary side of the first transformer or the second transformer to the primary side of the first transformer or the second transformer, the controller controls a transformer gain, based on at least one of the first transformer and the second transformer, to be stepped down.
A vehicle comprising the power converting device of any one of claims 1 to 19.